The present invention relates in general to wave energy conversion systems and, more particularly, to an articulating wave energy conversion system that minimizes incident wave energy attenuation using a compound lever-arm barge.
Richard Peter McCabe devised the McCabe Wave Pump, which is described in U.S. Pat. No. 5,132,550. The McCabe Wave Pump consists of three rectangular steel pontoons, which move relative to each other in the waves. A damper wave plate attached to the central pontoon ensures that it remains stationary as the fore and aft pontoons move relative to the central pontoon by pitching about the hinges. Energy is extracted from the rotation about the hinge points by linear hydraulic pumps mounted between the central and other two pontoons near the hinges.
A related configuration to the McCabe Wave Pump is an “articulating wave energy conversion system (AWECS)” which is disclosed in U.S. Pat. No. 8,778,176 (Murtha, et al.); U.S. Pat. No. 8,784,653 (Murtha, et al.); and U.S. Pat. No. 8,866,321 (McCormick, et al.), and all of which are owned by the same Assignee as the present application, namely, Murtech, Inc. of Glen Burnie, Md. See also U.S. Pat. No. 8,650,869 (McCormick). As shown in FIG. 1, an AWECS 1 uses a plurality of pneumatic or hydraulic pumps P (hereinafter, “hydraulic” is used, it being understood that “pneumatic” is also interchangeable with “hydraulic”) that straddle the two articulating barges, a forward barge 2 and a rear (also referred to as “aft”) barge 4 which are coupled together, e.g. by hinges to a central barge 3. Although not shown, a damper wave plate may be attached to the central barge 3 and submerged in the water which ensures that it remains stationary as the fore 2 and aft 4 barges move relative to the central barge 3 by pitching about the hinges. As an incoming wave makes contact with the forward barge 2 first, the hydraulic fluid in the pumps P coupled between the forward barge 2 and the center barge 3 are driven in a first direction; as the wave continues, the hydraulic fluid in the pumps P coupled between the rear barge 4 and the center barge 3 are driven in a second opposite direction. The end results are bi-directional hydraulic pumps P. The high pressure fluid output of these hydraulic pumps P may be used for a variety of functions such as, but not limited to, water desalination, irrigation of salt water vegetation or various energy conversions.
However, in the wave-energy conversion process, the design orientation of the system with the incident waves is such that the bow line is assumed to be parallel with the incident wave crest. As the waves pass the system, the barges 2/4 are excited, mainly in angular pitching motions. If pumps are connected to the barges, and placed over or under the hinges in FIG. 1, the pumps are excited by the barge motions. This is called the “power takeoff”, or PTO, mechanism. As the waves travel along the floating system, the available energy in the neighborhood of the barge is reduced because of the absorption of the forward barge (or barges). The absorbed energy is somewhat replaced by the process called wave diffraction, where wave energy travels along the crest from a high-energy local to a low-energy local—the latter being the neighborhood of the articulated barge.
As can be appreciated from the foregoing, the attenuation of the available wave energy along the length of the articulated-barge system length poses a problem. That is, less energy is available to the after barge or barges.
Thus, there remains a need for an articulated wave energy conversion system that can minimize the attenuation of available wave energy along the length of the articulated-barge system length so that the energy of the incident waves can be converted into significant mechanical energy (e.g., large pump pressures) for use in such things as potable water production, electrical energy generation, etc.
All references cited herein are incorporated herein by reference in their entireties.